Idle adjustment knob for Johnson 15hp

[TOY BOAT]

Ok guys and gals. I purchased a near mint 94 Johnson 15hp 2 stroke. Model #J15RERE. The only issue is the idle adjustment knob on the tiller handle just spins. It does not adjust. I assume it is broke, and needs replacement. I am hoping this is some what of a common issue that somebody can help me with what parts I am needing to replace. Maybe an idea of how to replace it.
Any help would be great.
Thank you

BTW
It is the last style handle #4

 

[merkdawg]

Re: Idle adjustment knob for Johnson 15hp

While the boat is sitting in the garage try pushing in on the knob and turning it to take hold of some threads. I believe it just screws down to keep the throttle locked in a set speed. IMO don't know if it's worth the trouble of tearing apart just to have cruise control. Lol